If you have any pics of yourself uploaded to a site (mine is from Myspace for example), go to that site, right click on the picture, go to "properties" and there will be a "url" box. Highlight that box and copy whats in it. Then, on here, click on the "image" box (it's the picture of the tree) and paste what you copied into the small window that appears (it says "undefined" if you don't type anything into it).
Sounds complicated, but if you follow the steps, you'll see it's not so bad.